I find at a number of pumping installations, the dirt box and the water meters are coupled together and installed. 

The water meter manufacturers specify a requirement of straight pipe of 10 times the diameter of the meter both upstream and downstream.  They also recommend installation of a dirt box (Strainer) upstream of the water meter for protection of the meter impeller. 

In many of the installations in our pump houses I find the dirt box and meter are joined together through a common flange and installed.  In the case of dirt box, the water passes through the strainer through a curved path.  The area of cross section also varies.  I want to know whether the 10d straight pipe has to be installed in between the dirt box and the water meter. And what are the implications of the same?

P. Gopalakrishnan
pgopalakrishnan@mail.twadboard.gov.in